I have put client ip's with their hostnames in my hosts file (RPI 4, Ubuntu):
What happens is, that if I open Query Log, the ip's hostname appears on the line where earlier the ip address is shown, but when using pihole -t there are still ip numbers shown. Is there a way to show host names as well or does this need a version update?
pihole -t is nothing else but a live tail of the log file. There are neither hostnames in the log file, nor does any post-processing happen here. The Query Log does a lot more than pihole -t and is aware of host names. It is not planed at this point to implement according post-processing into pihole -t.
However, I think there is a feature request to add a live updating version of the Query Log which would give you what you are looking for.
The log being tailed is the dnsmasq log at /var/log/pihole.log, and this contains only the requesting client IP. The query log has some additional processing done by Pi-hole to put the client name (if known) into the file. The dnsmasq log has none of that information.